1. Field of the Invention
The present invention relates to ink jet recording devices such as printers, copiers, facsimile machines, word processors and plotters, and more particularly to an ink jet printing apparatus having means in the form of a reserve supply compartment for storage of extra liquid material.
2. Description of Prior Developments
The basic principle of an ink jet recording system is to eject a liquid or fused solid ink from a nozzle, slit, porous film or the like to make a recording on a medium such as paper, cloth or film. For ejecting an ink, various methods have been proposed, such as a method of ejecting an ink using electrostatic induction; namely, the so-called charge control system; a method of ejecting an ink using a piezoelectric element and an oscillation pressure; and a method of ejecting an ink using a pressure generated as a result of forming and growing bubbles by heat, the so-called thermal ink jet system. Using any of these methods, an image having a high precision on a recording material can be obtained.
Ink jet printing systems generally are of two types, i.e., continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is disturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field which adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or to a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with information from digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
Since drop-on-demand systems require no ink recovery, charging, or deflection, the system is much simpler than the continuous stream type. There are two types of drop-on-demand ink jet systems. One type of drop-on-demand system has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. The relatively large size of the transducer prevents close spacing of the nozzles, and physical limitations of the transducer result in low ink drop velocity. Low drop velocity seriously diminishes tolerances for drop velocity variation and directionality, thus impacting the system""s ability to produce high quality copies. Drop-on-demand systems which use piezoelectric devices to expel the droplets also suffer the disadvantage of a slow printing speed.
Another type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets and allows very close spacing of nozzles. The major components of this type of drop-on-demand system are an ink filled channel having a nozzle on one end and a heat generating resistor near the nozzle. Printing signals representing digital information originate an electric current pulse in a resistive layer within each ink passageway near the orifice or nozzle, causing the ink in the immediate vicinity to evaporate almost instantaneously and create a bubble. The ink at the orifice is forced out as a propelled droplet as the bubble expands. When the hydrodynamic motion of the ink stops, the process is ready to start all over again. With the introduction of a droplet ejection system based upon thermally generated bubbles, commonly referred to as the xe2x80x9cbubble jetxe2x80x9d system, the drop-on-demand ink jet printers provide simpler, lower cost devices than their continuous stream counterparts, and yet have substantially the same high speed printing capability.
In all of the various ink jet printing systems described above, the ink jet printing apparatus employs a reservoir for containing the ink that is fed to a series of printheads for printing on a substrate such as paper. In view of the fact that the ink jet cassettes have reservoirs with limited capacities for ink or other fluids typically used in an ink jet apparatus, e.g. maintenance fluids such as claiming fluids there comes a time during use of an ink jet printer when for example, the ink is used up and the user is not able to complete the printing job being marked on.
In accordance with one embodiment of the features of the invention as described herein there is proposed to provide a reserve ink supply compartment positioned within an ink jet printhead ink tank. If a user runs out of ink during a printing job, the user can push a button on the ink supply tank (or turn a knob) which results in the wall of the reserve supply tank being pierced and ink contained therein being fed to the printheads to complete the printing job. Also in another embodiment of this invention, maintenance fluid for the ink jet printing apparatus (e.g. cleaning fluid) can be stored within the reserve tank and be used, for example, to clean up the printheads just prior to the installation of the next ink tank for the next printing job.
In accordance with the embodiments described herein there is defined a system for supplying a liquid material to an ink jet printing apparatus including a plurality of printheads the system comprising a housing defining a first chamber and a second chamber, the first chamber includes a ventilation port. The first chamber is adapted to store a supply of liquid ink therein, and includes a liquid reserve pocket adapted to supply the printheads with small amounts of the liquid material. The second chamber includes a foam material positioned therein.
In accordance with another embodiment of this invention there is defined a system for supplying ink to an ink jet printing apparatus including a housing for containing ink in a first chamber. The first chamber includes a reserve tank positioned therein. The reserve tank includes a supply of ink adapted to be fed to the first chamber when the first chamber runs out of ink. The housing includes a second chamber with a foam material positioned therein.
In accordance with still another embodiment of this invention there is defined a system for supplying a maintenance fluid to an ink jet printing apparatus which includes a plurality of printheads, the system comprising a housing for containing ink in a first chamber. The first chamber includes a reserve tank positioned therein. The reserve tank contains a maintenance fluid adapted to be fed from the reserve tank to the printhead.